The trick is to communicate that you genuinely want to interact with the user. None of those atrocious, disrespectful popups that show up 10 seconds after I click on a search result going "hey wanna subscribe to our newsletter?" - "NO ffs, I was searching for a solution to a tech problem but now at least I know your site is complete garbage and I can stop reading"

Be honest, put the text directly below the main content, make it unobtrusive and start with something along the lines of "hey, I'm the guy running this site, and I wonder why sometimes I get a lot of visitors ..."

With that, if you get any reply, it's probably the most honest one too.